Larviculture of Rhamdia quelen (Pisces, Pimelodidae) with vegetal and animal proteins, supplemented with plankton

Objective. To determine the effect on larval growth and survival of Rhamdia quelen of diets containing different proportions of animal and plant protein supplemented with plankton. Materials and methods. Two experimental diets were formulated, Diet-1 with 70% vegetable protein (soybean meal) and diet-2 with 70% animal protein (beef heart and fish meal); four feeding treatments (T) were studied: T1) 70% vegetable protein + filtering plankton sieve of 50-200 microns, T2) 70% vegetable protein + filtering plankton sieve of 50-200 microns, T3) 70% vegetable protein, T4) 70% animal protein. Larvae were handled at a density of 20 animals L-1 offering food daily to apparent satiation at 07:00, 11:00, 16:00 and 21:00 hours; supplementation with plankton was made at 11:00 and 21:00 hours. Results. There were no differences between T1 and T2 (p>0.05) in final weight (21.89±15.17mg vs 20.37±10.37mg), total length (13.41±2.34mm vs 13.39±1.99 mm), condition factor (K) (0.80±0.13 vs 0.78±0.13) and survival (46.6±2.68% vs 36.0±7.41%); between T3 and T4 the differences for these variables were not significant (3.35±1.40 mg vs 2.98±1.48 mg, 7.54±0.91mm vs 7.33±0.96mm, 0.75±0.13 vs 0.71±0.12, 33.6±24.8±9.07% vs 6.76%, respectively). In addition, significant differences were observed between the groups supplemented with plankton (T1 and T2) vs groups that received only vegetable or animal protein (T3 and T4) (p<0.05). Conclusions. Plankton supplementation was more effective than offering vegetable or animal ration. The inclusion of 62.9% of soybean meal in the formulation (T1), apparently did not affect growth or survival.